Differences

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--- teaching:se-kiba:manipulation-assignment:executive [2013/04/24 17:18] – [Moving the Arms (re-using code)] bartelsg
+++ teaching:se-kiba:manipulation-assignment:executive [2016/05/19 09:19] (current) – external edit 127.0.0.1
@@ Line 66: / Line 66: @@
   [l_shoulder_pan_joint, l_shoulder_lift_joint, l_upper_arm_roll_joint, l_elbow_flex_joint, l_forearm_roll_joint, l_wrist_flex_joint, l_wrist_roll_joint]
-Your next assignment is to load and use these parameters from the parameter server:
+Your next assignment is to load and use these parameters from the parameter server. We will do this in a new library package. This package will not contain any executable but just library code to be used by other packages.
-  * Copy ParameterServerUtils.h from the materials to your include directory.
+  * Create a new package called iai_seminar_manipulation_utils. Add a dependency on roscpp
-  * Create the equivalent cpp-file in src, and add it to the build requirements of our executive in the CMakeLists
+  * Copy ParameterServerUtils.h from the materials to include directory of that package.
+  * Create the equivalent cpp-file in src, and add it to the build requirements of the utils package in the CMakeLists __as a library__. The following [[http://answers.ros.org/question/33779/how-do-i-link-an-executable-with-library-in-other-package/|discussion on ROS answers]] should help you to (a) expose the functionalities as a library and (b) use it in another package.
+NOTE: ROS libraries are a great thing that basically offer two advantages. (1) They help __you__ re-use code in various of your ROS application. (2) If you provide some generic algorithm as library as a pure c/c++ library, you even allow __non-ROS-users__ to use your algorithm in their work. This is hard to achieve but the ultimate design goal: A clean cut between functionality/algorithm and meta-OS, i.e. ROS.
   * Now, implement all functionality described in ParameterServerUtils.h to load values from the parameter server. Consider using the data already one the server to test your functions. ([[http://www.ros.org/wiki/roscpp/Overview/Parameter%20Server|This]] should give you some good examples.)
-  * Afterwards, use the parameter-server-functions (and our original initGoal and startTrajectory) to implement the second version of initGoal and startTrajectory of the RobotArm class -- it should be quick!
+  * Afterwards, let the executive package depend on the library package. Use the parameter-server-functions (and our original initGoal and startTrajectory) in the executive package to implement the second version of initGoal and startTrajectory of the RobotArm class -- it should be quick!
   * Now, use the new initGoal(ros::NodeHandle&) and startTrajectory() in main.cpp. This should remove any need for hard-coded goals, and instead use the ones from the parameter server.